Scheme optimizes light chips

June 16/23, 2004

Researchers from the Technical University
of Denmark have borrowed a design tool developed for mechanical engineering
to improve the efficiency of nano-size optical waveguides.

The method could be used to manufacture cheap, efficient optical
components for telecommunications that could potentially increase data
transfer rates by three orders of magnitude, according to the researchers.
The devices could also be used to make minute lasers, lower-power light-emitting
diodes and tiny, efficient sensors.

The researchers' method uses topology optimization, a method for
solving the mechanical and civil engineering problem of finding structures
with optimal stiffness-to-weight ratios, to design photonic crystals.
Photonic crystals are light-guiding structures made from patterns of rods
or a solid that contains patterns of holes.

Traditionally, topology optimization algorithms add material where
stresses are high and subtract material in regions that are not loaded;
an optimal structure emerges after many repeats of the process. Rather
than distributing holes to obtain a optimal transfer of forces, the researchers'
method distributes holes in a material to find a structure with the optimal
light transfer.

The researchers' tests have shown that the method works for any
size or shape material. The method made it possible to improve the performance
of 120-degree bends in photonic bandgap waveguides tenfold, according
to the researchers.

Some practical applications could be ready in three to five years.
Full-scale, on-chip integration of the devices with electronics will take
10 to 15 years, according to the researchers. The work appeared in the
May 3, 2004 issue of Optics Express.